Pavement corer and method

ABSTRACT

A pavement coring machine having rotating cutting heads of various diameter, the optimum speed of rotation of the heads varying with the diameter of the cutting head and the nature of the pavement being cored has a direct reading tachometer positioned to be observed by an operator of the machine, the tachometer being operatively connected to display the speed of rotation of the cutting head. A method of operating the machine includes determining the optimum speed of rotation of a cutting head, and regulating the speed of the cutting head as displayed by the direct reading tachometer.

CROSS REFERENCE TO RELATED APPLICATIONS STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001] Not Applicable.

BACKGROUND OF THE INVENTION

[0002] This invention is an improvement on a commercially available machine, the SIMCO 250 PTC. The improved version is marketed as the SIMCO 255 PTC.

[0003] Among the various factors that affect bit (cutter head) performance and company profit, the speed of rotation of the cuffing head is an important one. If the speed is too high the cutter will polish. If the speed is low the job will take too long. It is necessary to keep the bit at the right speed, constantly. The down pressure exerted on the bit may vary, but the speed of rotation should remain constant. When rebar is encountered, it tends to slow the cutting process, but, again, maintaining the cutter speed is important.

[0004] Recommended core drilling speeds are as follows: Bit Minimum Optimum Maximum Diameter RPM RPM RPM  2″ 1200  1600  2000   3″ 600 1050  1300   4″ 600 800 1000   5″ 475 640 800  6″ 400 530 665  7″ 340 450 600  8″ 300 400 500 10″ 240 320 400 12″ 200 265 330 14″ 170 225 285 16″ 150 200 250 18″ 130 175 220 20″ 120 160 200

[0005] In pavement coring machines available heretofore, the speed of rotation has been controlled by the operator, judging the speed by experience.

[0006] One of the objects of this invention is to establish an optimum speed of rotation for cutting heads of different diameters, and enabling an operator to maintain those speeds by observing a direct read tachometer.

[0007] Another object is to provide such a machine in which upon setting the speed of rotation, that speed is automatically maintained, subject to an override by the operator.

[0008] Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.

BRIEF SUMMARY OF THE INVENTION

[0009] In accordance with this invention, generally stated, a pavement coring machine having rotating cutting heads of various diameters, the optimum speed of rotation of the heads varying with the diameter of the cutting head and the nature of the pavement being cored, is provided with a direct reading tachometer positioned to be observed by an operator of the machine, the tachometer being operatively connected to display the speed of rotation of the cutting head. Preferably, the speed of rotation for any particular diameter head is set by the operator and maintained automatically, subject to the operator's override.

[0010] The method of using the machine comprises determining the optimum speed of rotation of a cutting head of a particular diameter and for a particular use, and maintaining that speed of rotation as displayed on a direct reading tachometer.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0011] In the drawings:

[0012]FIG. 1 is a view in perspective of one illustrative embodiment of pavement corer of this invention;

[0013]FIG. 2 is a view in perspective of a core;

[0014]FIG. 3 is a view in perspective of the core being lifted from the pavement; and

[0015]FIG. 4 is a view in front elevation of a control panel of the corer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring now to the drawing for one illustrative embodiment of this invention, reference numeral 1 indicates a rig of this invention mounted on a truck 2. A prime mover, in the form of a gasoline or diesel engine or electric motor, for example, drives a hydraulic pump, not here shown, to supply hydraulic fluid to a hydraulic motor 3. These elements are all conventional. A cutting head 5 is rotated by the motor 3 through a shaft 8. A hydraulic cylinder, not here shown, in a mast 10 exerts a downward pressure on the motor, shaft, and cutter head. These elements, also, are conventional, as is a water swivel 14.

[0017] Control knobs 20 and 21 regulate the flow of hydraulic fluid from the pump to the motor 3 and to the hydraulic cylinder.

[0018] A digital readout tachometer 25 displays the rate of rotation of the shaft 8. Analog gauges 30 and 31 are calibrated to display the pressure of hydraulic fluid to the hydraulic cylinder in the mast, and to the motor 3.

[0019] Referring now to FIGS. 2 and 3, reference numeral 40 indicates a core, with a hole 43 in it. After the core 40 has been cut with the machine, the hole 43 is formed through a broad face 41 of the core 40, entirely through the core, and an eyebolt 46 is anchored in the hole 43. The core can then be lifted out of the hole by means of a cable lift, which, is shown somewhat diagrammatically as extending around a spool 50. The spool 50 can be either manually operated through a gearing system, not shown, or by hydraulic motor. In this illustrative embodiment, the spool 50 is shown as being mounted on an arm 52 revolvably connected to a post 54 mounted on a base 56. When the core 40 has been raised above the level of pavement, it can be swung to one side, to permit access to the hole from which it was taken.

[0020] Numerous variations in the construction of the machine of this invention, and the method of use, within the scope of the appended claims will occur to those skilled in the art in the light of the foregoing disclosure. Merely by way of illustration and not of limitation, the tachometer 25 can be analog, although the digital readout is preferred. Push-button controls can be provided for drills of each size expected to be used, so that merely by pushing the appropriate button, the speed of rotation is established and remains constant unless overridden by an operator. Any other means of setting the speed of rotation can be employed, and means for maintaining that speed. The optimum speed of rotation as used in the illustrative embodiment described indicates a speed within about plus or minus 10% of the optimum given in the table, above, not just the exact optimum speed. However, the optimum speeds of rotation for different types of cutter heads may vary, those speeds being recommended by the manufacture of the cutting head (bit or barrel). The optimum speed for those bits will then be in the range of about plus or minus 10% of the recommended speed. In drilling through asphalt or other material softer than concrete, it is possible to operate the cutting head at a slightly higher speed of rotation, but generally those speeds will be within the range of 10% of the ideal speed recommended by the manufacturer for coring concrete. These variations are merely illustrative. 

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:
 1. In a pavement coring machine having rotating cutting heads of various diameters, the optimum speed of rotation of said heads varying with the diameter of the cutting head and the nature of the pavement being cored, the improvement comprising a direct reading tachometer positioned to be observed by an operator of the machine, said tachometer being operatively connected to display the speed of rotation of said cutting head.
 2. In a pavement coring machine having rotating cutting heads of various diameters, the optimum speed of rotation of said heads varying with the diameter of the cutting head and the nature of the pavement being cored, the improvement comprising a manually settable speed control having indicia representing diameters of said cutting heads, whereby when said speed control is set at a chosen indicium, the cutting head is rotated at an optimum speed.
 3. The method of operating a pavement coring machine having heads of various diameters comprising determining the optimum speed of rotation of a cutting head, dependent upon the diameter of the cutting head, and regulating the speed of the cutting head as displayed by a direct reading tachometer.
 4. The method of claim 3 wherein the speed of rotation of the cutting head is maintained automatically, subject to a manual override by the operator of the machine.
 5. A method of coring a pavement comprising cutting a circular core by utilizing a pavement coring machine having rotating cutting heads of various diameters, the optimum speed of rotation of said heads varying with the diameter of the cutting head, determining the optimum speed of rotation of the particular cutting head being used, rotating said cutting head at said optimum speed, regulating the speed of the cutting head as displayed by a direct reading tachometer, thereafter drilling a hole through two broad faces of said core, anchoring an eye-bolt in said hole, and lifting said core by means of said eye-bolt. 